Note: The HEARTH Education Foundation (HEARTH) has generously allowed HearthNet to reprint the first chapter of the HEARTH Gas Appliance Specialist Training Manual. HEARTH is an independent, non-profit agency that promotes safe and responsible use of hearth products through professional training and public education. HEARTH maintains a web site and a list of certified specialists who have received training and passed exams in 5 areas of hearth products expertise: Fireplace, Gas, Pellet, Venting, and Woodstove.
HISTORY AND NATURE OF FUEL GASES (Natural Gas and LPG)
Origin and History of Gas Fuels
The search for ways to keep one’ s hearth warm and inviting has been an age old quest. The products of this quest have included a variety of solid fuels such as wood, coal, coke, peat, and charcoal. More recent discoveries (in terms of their practical or commercial value) have included the use of natural gas (NG) and liquefied petroleum gas (LPG). Their flammability, high energy value, and convenience have resulted in a historically rapid rise to extensive use as a fuel today.
The composition of natural gas varies in different localities. However, it is always a colorless, highly flammable gas consisting primarily of methane. Methane usually makes up from 80 to 95 percent of its volume (commonly listed as 81.1%). The balance is composed of varying amounts of methane, another hydrocarbon compound, and other gases carbon dioxide, nitrogen, helium, argon, hydrogen, carbon monoxide, and sometimes, hydrogen sulfide.
Origin and Location
The most accepted theory of the origin of natural gas assumes that natural gas hydrocarbons come from organic matter (the remains of land and aquatic plants and animals) that was captured in sediments and changed over long periods of time into their present form. Some geologists believe that natural gas is a byproduct or an end product of the formation of petroleum; others think it has a separate origin. Although commonly associated with the production of petroleum, natural gas is also found stored independently in sand, sandstone, and limestone deposits at a considerable distance from oil fields. Most of the gas reserves in the United States are not dissolved or in contact with oil.
History of Use as Fuel
Natural gas was actually known to the ancients, but it was considered by them to be a supernatural manifestation. Noticed only when ignited, it appeared as a mysterious fire bursting from fissures in the ground. Natural gas seeps were discovered in Iran between 6000 and 2000 B.C. The use of gas was mentioned in China about 900 B.C. Apparently, natural gas was unknown in Europe until its discovery in England in 1659. However, since manufactured gas (coal gas) was already commercially available, natural gas remained unpopular. In 1815, natural gas was discovered in the United States during the digging of a salt brine well in Charleston, West Virginia.
One of the earliest attempts to harness it for economic use occurred in 1824 in Fredonia, New York and led to the formation of the first natural gas company in the United States, the Fredonia Gas Light Company, in 1859. Toward the latter part of the nineteenth century large industrial cities began to use natural gas. Pipelines were constructed to conduct the gas to these areas. Steady growth in the use of gas marked the early and mid-twentieth century. However, it was the shortages of crude oil in the late 1960’s and early 1970’s that forced major industrial nations to seek energy alternatives. Since those events, gas has become a central fossil fuel energy source.
Current Recovery and Transport
Natural gas is recovered and used in the greatest quantity in the United States and what was formerly the Soviet Union, and in smaller amounts in Canada, Mexico, and parts of Europe, Asia, and Australia. It is estimated that the United States possesses about four percent of the world’s natural gas reserves, while the majority of reserves lie under Russia, Kazakhstan, and Iran.
In the United States, the largest gas producers are the states of Texas, Louisiana, California, Oklahoma, and West Virginia, but natural gas is found in large quantities in many other states as well. 80% of natural gas comes from gas reservoirs, while the remaining 20% comes from oil wells.
Today, a vast network of pipelines for the transport of natural gas exists. Some are over 5,000 miles long.
Natural gas can also be liquefied and transported by ocean going vessels.
It should be recognized that natural gas, as a fossil fuel, is not a renewable source of energy. Great care must be taken to avoid environmental problems associated with drilling activity and with the accidental release of methane, a more potent contributor to the greenhouse effect than carbon dioxide. Nonetheless, when natural gas burns completely, only carbon dioxide and water are produced. Normally, the combustion of natural gas is relatively (although not completely) free of soot, carbon monoxide, and the nitrogen oxides associated with burning of other fossil fuels. This makes natural gas one of the preferred fuels for home heating and aesthetic enjoyment.
LIQUEFIED PETROLEUM GAS (LPG)
Also a colorless, odorless, and non-toxic gas, liquefied petroleum gas (LPG) is separated in large quantities from natural gas, light crude oil, and oil-refinery gases.
The primary source of LPG is “wet” natural gas. Wet natural gas contains impurities and heavier hydrocarbons, such as propane and butane. To turn wet natural gas into a “dry” gas, these heavier hydrocarbons and impurities must be removed. This extraction is called distilling.
As early as 1860, LPG was used for a portable fuel source, and its use has expanded dramatically ever since. The extensive use of LPG did not develop until the 1940’s through the 1960’s. Liquefied petroleum gas is primarily and widely used in rural areas where piped natural gas is not available. Transport LPG is delivered to the consumer as a liquid in cylinders of various sizes, weighing from 1 pound to 1,000 pounds and maintained under relatively low pressures of about 100 psi (pounds per square inch).
(note:Above Reprinted with permission from HEARTH Gas Appliance Training Manual, Copyright 1997, HEARTH Education Foundation.)
Other Information about Natural Gas
Natural gas is colorless, odorless and nontoxic. The odor which is common to natural gas is caused by an additive which is purposely mixed in with the gas.
The ignition temperature of natural gas is approx. 1,150 degrees F. Natural gas requires a correct mixture of air and gas in order to burn efficiently.
The average heat value of natural gas is 1000 BTU per cubic foot. A BTU (British Thermal Unit) is enough heat to heat one pound of water one degree (F). Natural gas is sold to the customer in units of 1000 cubic feet or MCF. This represents approx. 1,000,000 BTU of heating power, enough to heat a normal home for about 24 hours during colder weather. Prices vary, from as low as $9.00 to as high as $20.00+ per mcf.
Natural Gas is delivered to the customer at a very low pressure, usually less than 1/2 PSI. The pressure is expressed in Water Column (WC), where 28” WC = 1 PSI.
Other Information about LPG
Propane and Butane, which are the primary gases in LPG, are heavier and contain more heat per cubic foot than natural gas. LPG contains 2,500 BTU per cubic foot, and is sold by the gallon. One gallon of LPG contains approx. 90,000 BTU and is sold for $1.25 to $2.00
LPG gas is heavier than air, which means it can pool into the lowest area in an appliance or room. It also has a lower ignition temperature than Natural gas.
Gas is a safe fuel if installed and handles correctly. However, improper use, installation and maintenance of LPG or Natural Gas lines or appliances can cause fire, explosion or asphyxiation. Please make certain that you have all work inspected and certified by a Gas Professional. You can find a Gas Specialist at:
1. Your local plumbing, fire or building code office
2. Your Gas or LP company
3. HEARTH EDUCATION FOUNDATION - HEARTH specialists study a comprehensive training manual and pass a rigorous exam covering the fundamentals of gas hearth appliances.